Smell of chemical or gas inside vehicle

I have a 2009 model Toyota Prius. There is a smell of chemical or gas inside my vehicle when I first get in. By "gas" I mean "gas" and not "petrol". So if it is a chemical from the battery for example, it smells like natural gas. I have been delivering phone books from my car in acreage which caused me to start and stop the car every 200 meters for about an hour. I only noticed the smell after I delivered the phone books. I searched the Prius Chat forum last night and read that stopping and starting for a lengthy period is bad for the battery. Should I ignore the smell and wait for the battery warning light to show. And if the battery warning light does flash, which battery would it relate to and is there a different warning light for both batteries? I have booked my car into the Toyota service center tomorrow but think I might cancel. They will probably run a diagnostic and see nothing as they will just interpret a number from a computer. They will predictably sniff and smell nothing ... and then I will pay them the service fee for nothing.